Golf ball

ABSTRACT

A high CoR golf ball having predetermined moment of inertia is provided. A portion of the golf ball preferably contains substantially no filler, which contributes to the increased resilience of the ball. In accordance to one aspect of the invention, the portion with substantially no filler is an intermediate layer of the ball, and preferably is the outer core layer of the ball. The remaining portions of the ball preferably contribute to the moment of inertia of the ball. To craft a low moment of inertia ball, the innermost core should have a high specific gravity. Additionally, the outermost layers of the ball may have a low specific gravity. Conversely, to craft a high moment of inertia ball, the ball should have a thin dense layer positioned radially outward from its centroid radius. Additionally, the innermost core may have a low specific gravity. To craft a mid range moment of inertia ball, the ball may comprise a high specific gravity inner core and a thin dense layer. Preferably, the portion with substantially no filler is relatively larger than other portions of the ball.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of co-pending patentapplication entitled “Golf Ball,” bearing application Ser. No.09/842,574, filed on Apr. 26, 2001, which is a continuation-in-part ofco-pending patent application entitled “Golf Ball and a Method forControlling the Spin Rate of Same,” bearing application Ser. No.09/815,753, filed on Mar. 23, 2001. The disclosures of the parentapplications are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

[0002] The present invention relates to golf balls and moreparticularly, the invention is directed to golf balls with improvedcoefficient of restitution and spin rate.

BACKGROUND OF THE INVENTION

[0003] The spin rate of golf balls is the end result of many variables,one of which is the distribution of the density or specific gravitywithin the ball. Spin rate is an important characteristic of golf ballsfor both skilled and recreational golfers. High spin rate allows themore skilled players, such as PGA professionals and low handicappedplayers, to maximize control of the golf ball. A high spin rate golfball is advantageous for an approach shot to the green. The ability toproduce and control back spin to stop the ball on the green and sidespin to draw or fade the ball substantially improves a player's controlover the ball. Hence, the more skilled players generally prefer a golfball that exhibits high spin rate, in part, off scoring irons, such asthe 7-iron club through the pitching wedge.

[0004] On the other hand, the recreational players who cannotintentionally control the spin of the ball generally do not prefer ahigh spin rate golf ball. For these players, slicing and hooking theball are the more immediate obstacles. When a club head strikes a ballimproperly, an unintentional side spin is often imparted to the ball,which sends the ball off its intended course. The side spin reduces aplayer's control over the ball, as well as the direct-line distance theball will travel. A golf ball that spins less tends not to driftoff-line erratically if the ball is not hit squarely with the club face.A low spin ball will not cure the hook or slice, but will reduce theadverse effects of the side spin. Hence, recreational players typicallyprefer a golf ball that exhibits low spin rate.

[0005] Reallocating the density or specific gravity of the variouslayers of a golf ball provides an important means of controlling thespin rate. In some instances, the weight from the outer portions of theball is redistributed toward the center to decrease the moment ofinertia, thereby increasing the spin rate. For example, U.S. Pat. No.4,625,964 discloses a golf ball with a reduced moment of inertia havinga core with specific gravity of at least 1.50 and a diameter of lessthan 32 mm and an intermediate layer of lower specific gravity betweenthe core and the cover. U.S. Pat. No. 5,104,126 discloses a ball with adense inner core having a specific gravity of at least 1.25 encapsulatedby a lower density syntactic foam composition. U.S. Pat. No. 5,048,838discloses another golf ball with a dense inner core having a diameter inthe range of 15-25 mm with a specific gravity of 1.2 to 4.0 and an outerlayer with a specific gravity of 0.1 to 3.0 less than the specificgravity of the inner core. U.S. Pat. No. 5,482,285 discloses anothergolf ball with reduced moment of inertia by reducing the specificgravity of an outer core to 0.2 to 1.0.

[0006] In other instances, the weight from the inner portion of the ballis redistributed outward to increase the moment of inertia, therebydecreasing the spin rate. U.S. Pat. No. 6,120,393 discloses a golf ballwith a hollow inner layer with one or more resilient outer layers,thereby giving the ball a soft core, and a hard cover. U.S. Pat. No.6,142,887 discloses an increased moment of inertia golf ball comprisingone or more layer layers made from metals, ceramic or compositematerials, and a polymeric spherical substrate disposed inwardly fromthe layer layers.

[0007] The redistribution of weight within the golf ball is typicallyaccomplished by adding fillers to the inner core or to an outer layer ofthe golf ball. Conventional fillers include the high specific gravityfillers, such as metal or metal alloy powders, metal oxide, metalsearates, particulates, carbonaceous materials, or low specific gravityfillers, such as hollow spheres, microspheres or foamed particles.However, the addition of fillers may adversely interfere with theinherent resiliency of the polymers used in golf balls and thereby thecoefficient of restitution of the golf balls. Hence, there remains aneed in the art for a golf ball with controlled moment of inertia thathas improved coefficient of restitution.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to a golf ball that has apredetermined moment of inertia and an improved coefficient ofrestitution.

[0009] The present invention is also directed to a golf ball that has apredetermined moment of inertia and a resilient zone.

[0010] The present invention is also directed to a golf ball that hascomprises a portion that has substantially no filler.

[0011] The present invention is further directed to a golf ball withmulti-layer core, wherein one core layer contains substantially nofiller, or in other words it contains filler in an amount that is lessthan or equal to five parts of filler to 100 parts of polymericmaterial.

[0012] The present invention is directed to a low moment of inertia golfball comprising a multilayer core encased by a thin cover having athickness in the range of about 0.010 inch to about 0.040 inch. The corecomprises a high density inner core and an outer core, which containssubstantially no filler. The specific gravity of the inner core ispreferably greater than about 5.0 and more preferably greater than about6.5. In accordance to one aspect of the invention, the inner corecomprises high specific gravity filler incorporated in a polymericmatrix. Preferably, the filler is a heavy metal powder, such astungsten. Alternatively, the inner core comprises a metal sphere. Thediameter of the inner core is preferably less than 0.75 inch, and morepreferably in the range of about 0.25 inch to about 0.50 inch, and mostpreferably in the range of about 0.40 inch to about 0.50 inch.Preferably, the cover is either a single layer or a multi-layer cover,and preferably the outer core comprises a highly resilient polymericcore material and additives that improves the outer core=s resilience.

[0013] The present invention is also directed to a high moment ofinertia golf ball comprising a thin dense layer encasing a core.Preferably, the specific gravity of the thin dense layer is higher thanthe specific gravity of the core, and the core preferably containssubstantially no filler. The core preferably has a diameter in the rangeof about 1.54 inch to about 1.64 inch. In accordance to one aspect ofthe present invention, the thin dense core comprises a Apre-preg@ thinfilm or a densified loaded film. To increase the moment of inertia, thegolf ball may further comprise a low specific gravity inner core. Theinner core may be hollow or filled with a low specific gravity liquid.The ball also comprises a single layer cover or preferably a multi-layercover having a thickness in the range of about 0.010 inch to about 0.040inch.

[0014] The present invention is also directed to a mid range moment ofinertia golf ball comprising a high density inner core, a thin densefilm and an outer core disposed therebetween. The outer core preferablyhas substantially no filler. Preferably the inner core is relativelysmall and the cover is relatively thin.

[0015] The present invention is also directed to a golf ball having athin dense layer encasing a multi-layer core. The inner core preferablyhas a specific gravity of less than about 0.9 and may have substantiallyno filler. The outer core preferably has a specific gravity from about0.5 to about 1.05, and may have substantially no filler. In accordanceto one aspect of the invention, the specific gravity of the outer coreis higher than the specific gravity of the inner core.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In the accompanying drawings, which form a part of thespecification and are to be read in conjunction therewith and in whichlike reference numerals are used to indicate like parts in the variousviews:

[0017]FIG. 1 is a cross-sectional view of a golf ball in accordance tothe present invention;

[0018]FIG. 2 is a plane view of an impact caused by a club striking agolf club; and

[0019]FIG. 3 is a cross-sectional view of a sandwich cover suitable foruse with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] It is well known that the total weight of the ball has to conformto the weight limit set by the United States Golf Association (“USGA”).Redistributing the weight or mass of the ball either toward the centerof the ball or toward the outer surface of the ball changes the dynamiccharacteristics of the ball at impact and in flight. Specifically, ifthe density is shifted or redistributed toward the center of the ball,the moment of inertia is reduced, and the initial spin rate of the ballas it leaves the golf club would increase due to lower resistance fromthe ball's moment of inertia. Conversely, if the density is shifted orredistributed toward or within the outer cover, the moment of inertia isincreased, and the initial spin rate of the ball as it leaves the golfclub would decrease due to the higher resistance from the ball's momentof inertia. The radial distance from the center of the ball or from theouter cover, where moment of inertia switches from being increased andto being decreased as a result of the redistribution of weight or massdensity, is an important factor in golf ball design.

[0021] In accordance to one aspect of the present invention, this radialdistance, hereinafter referred to as the centroid radius, is provided.When more of the ball's mass or weight is reallocated to the volume ofthe ball from the center to the centroid radius, the moment of inertiais decreased, thereby producing a high spin ball. When more of theball's mass or weight is reallocated to the volume between the centroidradius and the outer cover, the moment of inertia is increased therebyproducing a low spin ball.

[0022] The centroid radius can be determined by the following steps:

[0023] (a) Setting Ro to half of the 1.68-inch diameter for an averagesize ball, where Ro is the outer radius of the ball.

[0024] (b) Setting the weight of the ball to the USGA legal weight of1.62 ounce.

[0025] (c) Determining the moment of inertia of a ball with evenlydistributed density prior to any weight distribution.

[0026] The moment of inertia is represented by (⅖)(Mt)(Ro²), where Mt isthe total mass or weight of the ball. For the purpose of this invention,mass and weight can be used interchangeably. The formula for the momentof inertia for a sphere through any diameter is given in the CRCStandard Mathematical Tables, 24^(th) Edition, 1976 at 20 (hereinafterCRC reference). The moment of inertia of such a ball is 0.4572ounce-inch². This will be the baseline moment of inertia value.

[0027] (d) Taking a predetermined amount of weight uniformly from theball and reallocating this predetermined weight in the form of a thinshell to a location near the center of the ball and calculating the newmoment of inertia of the weight redistributed ball.

[0028] This moment of inertia is the sum of the inertia of the ball withthe reduced weight plus the moment of inertia contributed by the thinshell. This new moment of inertia is expressed as(⅖)(Mr)(Ro²)+(⅔)(Ms)(Rs²), where Mr is the reduced weight of the ball;Ms is the weight of the thin shell; and Rs is the radius of the thinshell measured from the center of the ball. Also, Mt=Mr+Ms. The formulaof the moment of inertia from a thin shell is also given in the CRCreference.

[0029] (e) Comparing the new moment of inertia determined in step (d) tothe baseline inertia value determined in step (c) to determine whetherthe moment of inertia has increased or decreased due to the reallocationof weight, i.e., subtracting the baseline inertia from the new inertia.

[0030] (f) Repeating steps (d) and (e) with the same predeterminedweight incrementally moving away from the center of the ball until thepredetermined weight reaches the outer surface of the ball.

[0031] (g) Determining the centroid radius as the radial location wherethe moment of inertia changes from increasing to decreasing.

[0032] (h) Repeating steps (d), (e), (f), and (g) with differentpredetermined weights and confirming that the centroid radius is thesame for each predetermined weight.

[0033] In a preferred embodiment of the present invention, thepredetermined weight is initially set at a very small weight, e.g., 0.01ounce, and the location of the thin shell is initially placed at 0.01inch radially from the center of the ball. The 0.01 ounce thin shell isthen moved radially and incrementally away from the center. The momentof inertia and changes in the moment of inertia are determined at eachincrement. The same procedure is repeated for predetermined weights of0.20 ounce, 0.405 ounce (or ¼ the weight of the ball), 0.81 ounce (or ½of the total weight of the ball) and 1.61 ounce (or practically all theweight of the ball). The results are fully disclosed in the two parentapplications, whose disclosures have been incorporated by reference. Theresults show that for each predetermined weight, the centroid radius islocated at the same radial distance, i.e., at approximately 0.65 inchradially from the center of a ball weighing 1.62 ounce and with adiameter of 1.68 inches, or 0.19 inch radially from the surface of theball.

[0034] Another advantageous result readily derived from the aboveprocedure is that at a radial distance of less than about 0.25 inch, ormore significantly less than about 0.20 inch, from the center of theball the rate of the reduction in moment of inertia is considerably lessthan the rate of the reduction in moment of inertia from a radialdistance from 0.25 inch to 0.65 inch. In other words, substantially allof the reduction in moment of inertia can be achieved by redistributingthe weight of the ball to within an innermost core of about 0.40 inch to0.50 inch in diameter.

[0035] In accordance to another aspect of the present invention, thegolf ball 10 comprises a multi-layer core, as illustrated in FIG. 1,having at least an inner core 12 and an outer core layer 14. Themulti-layer core is encased in a cover layer, which preferably is amulti-layer cover comprising at least inner cover layer 16 and outercover layer 18. A preferred way to redistribute the weight of the golfball is by adding fillers to a selected portion of the golf ball toachieve a desirable moment of inertia. As used herein the term “fillers”include any compound or composition that can be used to vary the densityor specific gravity of selected portions of the golf ball. Fillersinclude high density and low density fillers.

[0036] Suitable high density fillers may have specific gravity in therange from about 2 to about 19, and include, for example, metal (ormetal alloy) powder, metal oxide, metal searates, particulates,carbonaceous materials, and the like or blends thereof. Examples ofuseful metal (or metal alloy) powders include, but are not limited to,bismuth powder, boron powder, brass powder, bronze powder, cobaltpowder, copper powder, inconel metal powder, iron metal powder,molybdenum powder, nickel powder, stainless steel powder, titanium metalpowder, zirconium oxide powder, aluminum flakes, tungsten metal powder,beryllium metal powder, zinc metal powder, or tin metal powder. Examplesof metal oxides include but are not limited to zinc oxide, iron oxide,aluminum oxide, titanium dioxide, magnesium oxide, zirconium oxide, andtungsten trioxide. Examples of particulate carbonaceous materialsinclude but are not limited to graphite and carbon black. Examples ofother useful fillers include but are not limited to graphite fibers,precipitated hydrated silica, clay, talc, glass fibers, aramid fibers,mica, calcium metasilicate, barium sulfate, zinc sulfide, silicates,diatomaceous earth, calcium carbonate, magnesium carbonate, regrind(which is recycled uncured center material mixed and ground to 30 meshparticle size), manganese powder, and magnesium powder.

[0037] A more preferred high density filler is tungsten, tungsten oxideor tungsten metal powder due to its particularly high specific gravityof about 19.

[0038] Suitable low density fillers may include hollow spheres ormicrospheres that can be incorporated into a polymeric matrix of epoxy,urethane, polyester or any suitable binder, where the cured compositionhas a specific gravity of less than 0.9 or more preferably less than0.8. Low density fillers in accordance to the present invention may alsoinclude air pockets that are present in foamed polymers, such as apolyurethane foam or an integrally skinned polyurethane foam that formsa solid skin of polyurethane over a foamed substrate of the samecomposition. Foamed polymers also include a nucleated reaction injectionmolded polyurethane or polyurea, where a gas, typically nitrogen, isessentially whipped into at least one component of the polyurethane,typically, the pre-polymer, prior to component injection into a closedmold where full reaction takes place resulting in a cured polymer havinga reduced specific gravity. Foamed polymers also include chemically orphysically foamed thermoplastic or thermosetting polymers.

[0039] To craft a high moment of inertia or low spin golf ball, highdensity fillers may be added to outer portions of the ball preferablyradially outside of the centroid radius, e.g., an outer core layer or aninner cover layer. Alternatively, low density fillers may be added tothe inner portions of the ball preferably radially inside of thecentroid radius, e.g., an inner core layer. Conversely, to craft a lowmoment of inertia or high spin golf ball, low density fillers may beadded to the outer portions of the ball or high density fillers may beadded to inner portions of the golf ball. Additionally, fillers are alsoused to bring the weight of golf balls to 1.62 ounces, which is theupper weight limit set forth by the United States Golf Association(USGA).

[0040] One drawback of using fillers in the golf ball is that thefillers reduce the resilience and the coefficient of restitution (CoR)of the golf ball, and more particularly the CoR of the core or layerswhere the fillers are added. The CoR in solid core golf balls is afunction of the composition of the molded core and of the cover. Asdiscussed above, the molded core and the cover may comprise one or morelayers. The CoR is related to the initial velocity of the ball, whichmust not exceed 250±5 ft/s, which the maximum limit set forth by theUSGA. Hence, the CoR of golf balls are maximized and controlled, so thatthe initial velocity of the ball does not exceed the USGA limit.

[0041] A preferred material for the core is rubber, such aspolybutadiene. Preferred compositions of the innermost core and theother core layers in accordance to the present invention are discussedbelow. When fillers, such as zinc oxide when not used in quantitysufficient to effect a full cure of a zinc diacrylate/peroxide PBDsystem as described below, are mixed with the rubber materials theresilience of the rubber decreases. More specifically, for a range ofPGA compression of 30-100 a core made with a high content ofpolybutadiene and a low content of high density filler has a higher CoRthan a core made with a lower content of polybutadiene and a highercontent of lower density filler, as disclosed in U.S. patent publicationno. 2001/0016524. This disclosure is incorporated herein by reference.

[0042] Compression is measured by applying a spring-loaded force to thegolf ball center, golf ball core or the golf ball to be examined, with amanual instrument (an “Atti gauge”) manufactured by the Atti EngineeringCompany of Union City, N.J. This machine, equipped with a Federal DialGauge, Model D81-C, employs a calibrated spring under a known load. Thesphere to be tested is forced a distance of 0.2 inch (5 mm) against thisspring. If the spring, in turn, compresses 0.2 inch, the compression israted at 100; if the spring compresses 0.1 inch, the compression valueis rated as 0. Thus more compressible, softer materials will have lowerAtti gauge values than harder, less compressible materials. Compressionmeasured with this instrument is also referred to as PGA compression.The approximate relationship that exists between Atti or PGA compressionand Riehle compression can be expressed as:

(Atti or PGA compression)=(160-Riehle Compression).

[0043] To maximize the resilience and CoR of the ball, the core inaccordance to the present invention preferably has a deformation zonethat is substantially free of fillers. In other words, this zonepreferably has the highest possible content of polymeric core materialsand more preferably the highest content of polybutadiene rubber. As usedherein, the term “substantially free of fillers” means that the fillercontent is no more than about 5 phr to a 100 phr of rubber either beforeor after the cross-linking or curing process. The upper limit of fillercontent accounts for the impurities inherent in the materials that makeup the core composition and has no other function other than weightcontribution. For example, for a core composition that contains zincacrylate or zinc diacrylate, a small amount of zinc oxide is added tothe composition as an activator. Zinc oxide also reacts with andneutralizes any free acrylic acid that may be present in the zincacrylate or zinc diacrylate to form zinc acrylate or zinc diacrylate.The zinc acrylate or zinc diacrylate is believed to become a part of thepolymeric structure after the cross-linking process. The un-reacted zincoxide remains in the core and acts as a high density filler. Hence, coredeformation zones that have less than 5 phr filler to a 100 phr ofrubber are within the scope of the present invention. More preferably,the core deformation zones have less than 3 phr of filler to a 100 phrrubber.

[0044] Referring to FIG. 1, outer core 14 of a low moment of inertiaball is the core deformation zone and is substantially free of fillers.Preferably, outer core 14 occupies as large a volume of the golf ball aspossible. Hence, the inner core 12 preferably has a high specificgravity, or contains a high content of high specific gravity fillers toensure that ball 10 adheres to the 1.62 ounce USGA limit. Inner core 12preferably occupies as small a volume as possible. As illustrated inFIG. 2, when club head 20 strikes ball 10, a portion of ball 10 isdeformed by the impact with face 22. The deformed portion 24 of outercore 14 is responsible for most of the rebounding of the golf ball coreafter impact. Hence, as long as the inner core 12 is remote from thedeformed portion 24, there is no need to reduce further the size ofinner core 12, and thereby unnecessarily increasing the specific gravityof the inner core. Preferably, inner core 12 has a diameter of less thanabout 0.75 inch, more preferably between about 0.25 inch and 0.50 inch,and most preferably between about 0.40 inch and about 0.50 inch.

[0045] In accordance to another aspect of the present invention,minimizing the thickness of the cover layers 16, 18, can also optimizethe volume of the core deformation zone. Preferably, the thickness ofcover layers 16, 18 ranges from about 0.010 inch to about 0.040 inch,and more preferably ranges from about 0.010 inch to about 0.030 inch.Preferred compositions and properties of the cover layers in accordanceto the present invention are described below. Relatively large coreswith diameters in the range of 1.60 to 1.64 inches in diameter can berealized with these thin cover layers. However, cores with the diameterin the range of 1.54 inches to 1.64 inches are within the scope of thepresent invention. It has been discovered that the CoR varies with therate of deformation of the golf ball. More specifically, the CoR ishigher at higher rates of deformation and higher rate of recovery thanat lower rates. Hence, when more of the high resilient polymericmaterial is present in the deformed portion 24 of outer core layer 14,the deformed portion would recover faster. This faster rate of recoveryincreases the CoR of the core and thereby improving the CoR of the ball.

[0046] The compositions of outer core 14 described below are suitablefor a high moment of inertia ball, a low moment of inertia ball, andmid-range moment of inertia ball, in accordance to one aspect of thepresent invention,

[0047] In one preferred embodiment, the outer core 14 is made from apolybutadiene rubber (PBD) that has a mid Mooney viscosity range greaterthan about 40, more preferably in the range from about 40 to about 80and more preferably in the range from about 40 to about 60 Mooney.Polybutadiene rubber with higher Mooney viscosity may also be used, solong as the viscosity of the PBD does not reach a level where the highviscosity PBD clogs or otherwise adversely interferes with themanufacturing machinery. It is contemplated that PBD with viscosity lessthan 65 Mooney can be used with the present invention. A “Mooney” unitis a unit used to measure the plasticity of raw or unvulcanized rubber.The plasticity in a “Mooney” unit is equal to the torque, measured on anarbitrary scale, on a disk in a vessel that contains rubber at atemperature of 100° C. and rotates at two revolutions per minute. Themeasurement of Mooney viscosity is defined according to ASTM D-1646.

[0048] Golf ball cores made with mid to high Mooney viscosity PBDmaterial exhibit increased resiliency, hence distance, withoutincreasing the hardness of the ball. Such cores are soft, i.e.,compression less than about 60 and more specifically in the range ofabout 50-55, and when these soft cores are incorporated into golf ballssuch cores generate very low spin and long distance when struck by adriver. Cores with compression in the range of from about 30 about 50are also within the range of this preferred embodiment.

[0049] Commercial sources of suitable mid to high Mooney PBD includeBayer AG. “CB 23”, which has a Mooney viscosity of about 51 and is ahighly linear polybutadiene, is a preferred PBD. If desired, thepolybutadiene can also be mixed with other elastomers known in the art,such as natural rubber, styrene butadiene, and/or isoprene in order tofurther modify the properties of the core. When a mixture of elastomersis used, the amounts of other constituents in the core composition aretypically based on 100 parts by weight of the total elastomer mixture.

[0050] Other suitable core materials including thermoset plastics, suchas natural rubber, other grades of polybutadiene, polyisoprene,styrene-butadiene or styrene-propylene-diene rubber, and thermoplasticssuch as ionomer resins, polyamides, polyesters, or a thermoplasticelastomer. Suitable thermoplastic elastomers include Pebax®, which isbelieved to comprise polyether amide copolymers, Hytrel®, which isbelieved to comprise polyether ester copolymers, thermoplastic urethane,and Kraton®, which is believed to comprise styrenic block copolymerselastomers. These products are commercially available from Elf-Atochem,E. I. Du Pont de Nemours and Company, various manufacturers, and ShellChemical Company, respectively. The core materials can also be formedfrom a metal salt of a fatty acid, any partially or fully neutralizedionomer, a metallocene or other catalyzed polymer and a castablematerial. Suitable castable materials include those comprising aurethane, polyurea, epoxy, silicone, IPN's, etc. Golf ball cores madewith these core materials has a PGA compression of preferably less than90, more preferably less than 80 and most preferably less than 70.

[0051] Additionally, other suitable core materials (and cover materials)are disclosed in U.S. Pat. No. 5,919,100 and international publicationsWO 00/23519 and WO 01/29129. These disclosures are incorporated byreference herein in their entireties. One particularly suitable materialdisclosed in WO/29129 is a melt processible composition comprising ahighly neutralized ethylene copolymer and one or more aliphatic,mono-functional organic acids having fewer than 36 carbon atoms of saltsthereof, wherein greater than 90% of all the acid of the ethylenecopolymer is neutralized.

[0052] In accordance to another aspect of the invention, the addition ofsulfur compound to the core further increases the resiliency and thecoefficient of restitution of the ball. Preferred sulfur compoundsinclude, but are not limited to, pentachlorothiophenol (PCTP) and a saltof PCTP. A preferred salt of PCTP is ZnPCTP. The utilization of PCTP andZnPCTP in golf ball cores to produce soft and fast cores is disclosed inco-pending U.S. application No. 09/951,963 filed on Sep. 13, 2001, andis assigned to the same assignee as the present invention. Thisco-pending application is incorporated by reference herein, in itsentirety. A suitable PCTP is sold by the Structol Company under thetradename A95. ZnPCTP is commercially available from EchinaChem.

[0053] Metal salt diacrylates, dimethacrylates, and monomethacrylatessuitable for use in this invention include those wherein the metal ismagnesium, calcium, zinc, aluminum, sodium, lithium or nickel. Zincdiacrylate (ZDA) is preferred, but the present invention is not limitedthereto. ZDA provides golf balls with a high initial velocity. The ZDAcan be of various grades of purity. For the purposes of this invention,the lower the quantity of zinc stearate present in the ZDA the higherthe ZDA purity. ZDA containing less than about 10% zinc stearate ispreferable. More preferable is ZDA containing about 4-8% zinc stearate.Suitable, commercially available zinc diacrylates include those fromSartomer Co. The preferred concentrations of ZDA that can be used areabout 25 pph to about 35 pph based upon 100 pph of polybutadiene oralternately, polybutadiene with a mixture of other elastomers that equal100 pph. Advantageously, the PCTP organic sulfur reacts with the ZDAused in the core to further increase the initial velocity of golf balls.

[0054] Free radical initiators are used to promote cross-linking of themetal salt diacrylate, dimethacrylate, or monomethacrylate and thepolybutadiene. Suitable free radical initiators for use in the inventioninclude, but are not limited to peroxide compounds, such as dicumylperoxide, 1,1-di (t-butylperoxy)3,3,5-trimethyl cyclohexane, a—a bis(t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5 di (t-butylperoxy)hexane, or di-t-butyl peroxide, and mixtures thereof. Other usefulinitiators would be readily apparent to one of ordinary skill in the artwithout any need for experimentation. The initiator(s) at about 70% toabout 100% activity are preferably added in an amount ranging betweenabout 0.05 pph and about 2.5 pph based upon 100 parts of butadiene, orbutadiene mixed with one or more other elastomers. More preferably, theamount of initiator added ranges between about 0.15 pph and about 2 pphand most preferably between about 0.25 pph and about 1.5 pph. Suitablecommercially available dicumyl peroxides include Perkadox BC, which is a90% active dicumyl peroxide, and DCP 70, which is a 70% active dicumylperoxide.

[0055] As discussed above, when ZDA or another metal salt ofdiacrylates, dimethacrylates, and monomethacrylates are used in thecore, about 5 phr of zinc oxide or less (or a smaller amount of calciumoxide and higher amount of peroxide) is preferably added to the corecomposition to react and neutralize any acrylic acid that may bepresent.

[0056] Antioxidants may also be included. Antioxidants are compounds,which prevent the breakdown of the elastomer. Antioxidants useful in thepresent invention include, but are not limited to, quinoline typeantioxidants, amine type antioxidants, and phenolic type antioxidants.

[0057] Other ingredients such as accelerators, e.g., tetramethylthiuram, processing aids, processing oils, dyes and pigments, aswell as other additives well known to the skilled artisan may also beused in the present invention in amounts sufficient to achieve thepurpose for which they are typically used.

[0058] The outer core 14 of the present invention preferably containssubstantially no fillers. Preferably, the thickness of the outer core isbetween about 0.55 inch and 0.62 inch, and more preferably about 0.575inch. Alternatively, when an outer thin dense layer is used as describedbelow, outer core 14 may be thin, e.g., about 0.05 inch thick, or it maybe combined with inner core 12 to form a single layer core havingsubstantially no filler. The preferred specific gravity of the outercore is between about 1.0 and about 1.1. Specific gravity between about0.5 and about 1.05, and more specifically between about 0.8 and about0.96 is also suitable for the outer core.

[0059] For a low moment of inertia or high spin ball, inner core 12preferably has a high specific gravity in the range of greater thanabout 5.0, more preferably greater than about 6.5. As stated above, thepreferred diameter of inner core 12 is about 0.4 to about 0.5 inch.Diameters of less than about 0.75 inch or less than about 0.4 inch arealso suitable for this embodiment.

[0060] In a preferred embodiment of the invention, inner core 12comprises high density tungsten powder fillers (specific gravity ofhigher than 19) incorporated into a polymeric matrix, preferablypolyurethane. Other high density metal powders, such as lead, can beused. Alternatively, core materials suitable for outer core 14 discussedabove are also suitable for inner core 12. Tungsten powder content canbe as high as greater than about 1200 phr to 100 phr of polymer.

[0061] Alternatively, the core may comprise carbon, stainless or chromesteel spheres that are commercially available as ball bearings in sizesfrom 1 mm to 20 mm. Preferred sizes in English units are ¼ inch, ⅜ inch,{fraction (5/16)} inch, {fraction (7/16)} inch, ½ inch, ¾ inch or{fraction (11/16)} inch in diameter. Ball bearings made out of mildsteel have a specific gravity of about 7.80. Also, stainless steels suchas type 1225 has a specific gravity of about 6.5, and type 1650 has aspecific gravity of about 7.5.

[0062] For a high moment of inertia or low spin ball, inner core 12preferably has a low specific gravity. As stated above, inner core 12preferably comprises a polymer containing a density reducing filler, orotherwise has its specific gravity reduced, e.g., by foaming thepolymer. The effective specific gravity for this low specific gravitylayer is preferably less than about 0.9 and more preferably less thanabout 0.8.

[0063] Alternatively, inner core 12 may be hollow and filled with air(specific gravity of about 0.0013) or alcohol (specific gravity of about0.79).

[0064] As stated above, preferably the thickness of cover layers 16, 18ranges from about 0.010 inch to about 0.040 inch, and more preferablyranges from about 0.010 inch to about 0.030 inch. The thinness of thecover layers provides more volume, and thereby more resilient polymericcore materials can be included in the core layers.

[0065] In a first embodiment the inner and outer cover layers aredisclosed in U.S. Pat. No. 5,885,172, which is incorporated herein byreference in its entirety. The outer cover layer 18 is preferably formedfrom a relatively soft thermoset material in order to replicate the softfeel and high spin play characteristics of a balata ball when the ballsof the present invention are used for pitch and other “short game”shots. In particular, the outer cover layer should have a Shore Dhardness of from less than about 65 or about 30 to about 60, preferablyabout 35 to about 50 and most preferably about 40 to about 45. Hardnessis preferably measured pursuant to ASTM D-2240 in either button or slabform. Additionally, the materials of the outer cover layer must have adegree of abrasion resistance in order to be suitable for use as a golfball cover.

[0066] The outer cover layer of the present invention can comprise anysuitable thermoset material, which is formed from a castable reactiveliquid material. The preferred materials for the outer cover layerinclude, but are not limited to, thermoset urethanes and polyurethanes,thermoset urethane ionomers and thermoset urethane epoxies. Examples ofsuitable polyurethane ionomers are disclosed in U.S. Pat. No. 5,692,974,the disclosure of which is hereby incorporated by reference herein inits entirety in the present application.

[0067] Thermoset polyurethanes and urethanes are particularly preferredfor the outer cover layers of the balls of the present invention.Polyurethane is a product of a reaction between a polyurethaneprepolymer and a curing agent. The polyurethane prepolymer is a productformed by a reaction between a polyol and a diisocyanate. The curingagent is typically either a diamine or glycol. Often a catalyst isemployed to promote the reaction between the curing agent and thepolyurethane prepolymer.

[0068] Conventionally, thermoset polyurethanes are prepared using adiisocyanate, such as 2,4-toluene diisocyanate (TDI) ormethylenebis-(4-cyclohexyl isocyanate) (HMDI) and a polyol which iscured with a polyamine, such as methylenedianiline (MDA), or atrifunctional glycol, such as trimethylol propane, or tetrafunctionalglycol, such as N,N,N′,N′-tetrakis(2-hydroxpropyl)ethylenediamine.However, the present invention is not limited to just these specifictypes of thermoset polyurethanes. Quite to the contrary, any suitablethermoset polyurethane may be employed to form the outer cover layer ofthe present invention.

[0069] The inner cover layer 16 of the present invention is formed froma hard, high flexural modulus, resilient material that contributes tothe low spin, distance characteristics of the presently claimed ballswhen they are struck for long shots (e.g. driver or long irons).Specifically, the inner cover layer materials have a Shore D hardness ofabout 65-80, preferably about 69-74 and most preferably about 70-72.Furthermore, as defined herein, the term “high flexural modulus” means aflexural modulus (as measured by ASTM 790) of at least about 60,000 psi,preferably about 70,000 psi to about 120,000 psi and most preferably atleast about 75,000 psi. The thickness of the inner cover layer can rangefrom about 0.010 inch to about 0.045 inch, preferably about 0.150 inchto about 0.040 inch and most preferably about 0.020 inch.

[0070] The inner cover layer may be formed from a wide variety of hard,high flexural modulus resilient materials. Among the preferred innercover materials are hard, high flexural modulus ionomer resins andblends thereof. These ionomers are obtained by providing a crossmetallic bond to polymers of monoolefin with at least one memberselected from the group consisting of unsaturated mono- or di-carboxylicacids having 3 to 12 carbon atoms and esters thereof (the polymercontains 1 to 50% by weight of the unsaturated mono- or di-carboxylicacid and/or ester thereof). More particularly, such acid-containingethylene copolymer ionomer component includes E/X/Y copolymers where Eis ethylene, X is a softening comonomer such as acrylate or methacrylatepresent in 0-50 (preferably 0-25, most preferably 0-20), weight percentof the polymer, and Y is acrylic or methacrylic acid present in 5-35(preferably at least about 16, more preferably at least about 16-35,most preferably at least about 16-20) weight percent of the polymer,wherein the acid moiety is neutralized 1-90% (preferably at least 40%,most preferably at least about 60%) to form an ionomer by a cation suchas lithium*, sodium*, potassium, magnesium*, calcium, barium, lead, tin,zinc* or aluminum (*=preferred), or a combination of such cations.Specific acid-containing ethylene copolymers include ethylene/acrylicacid, ethylene/methacrylic acid, ethylene/acrylic acid/n-butyl acrylate,ethylene/methacrylic acid/n-butyl acrylate, ethylene/methacrylicacid/iso-butyl acrylate, ethylene/acrylic acid/iso-butyl acrylate,ethylene/methacrylic acid/n-butyl methacrylate, ethylene/acrylicacid/methyl methacrylate, ethylene/acrylic acid/methyl acrylate,ethylene/methacrylic acid/methyl acrylate, ethylene/methacrylicacid/methyl methacrylate, and ethylene/acrylic acid/n-butylmethacrylate. Preferred acidcontaining ethylene copolymers includeethylene/methacrylic acid, ethylene/acrylic acid, ethylene/methacrylicacid/n-butyl acrylate, ethylene/acrylic acid/n-butyl acrylate,ethylene/methacrylic acid/methyl acrylate and ethylene/acrylicacid/methyl acrylate copolymers. The most preferred acid-containingethylene copolymers are ethylene/methacrylic acid, ethylene/acrylicacid, ethylene/(meth)acrylic acid/n-butyl acrylate,ethylene/(meth)acrylic acid/ethyl acrylate, and ethylene/(meth)acrylicacid/methyl acrylate copolymers.

[0071] The manner in which the ionomers are made is well known in theart as described in e.g., U.S. Pat. No. 3,262,272. Such ionomer resinsare commercially available from DuPont Co. under the tradename SURLYN®and from Exxon under the tradename lotek®. Some particularly suitableSURLYNS® include SURLYN® 8140 (Na) and SURLYN® 8546 (Li), which have amethacrylic acid content of about 19%.

[0072] However, the materials for the inner cover layer are not limitedto ionomer resins. Instead, the present invention contemplates thatvirtually any hard, high flexural modulus, resilient material that iscompatible with the other materials of the golf ball may be employed asthe inner cover layer. Examples of other suitable inner cover materialsinclude thermoplastic or thermoset polyurethanes, thermoplastic orthermoset polyetheresters or polyetheramides, thermoplastic or thermosetpolyester, a dynamically vulcanized elastomer, a functionalizedstyrenebutadiene elastomer, a metallocene polymer or blends thereof.

[0073] Suitable thermoplastic polyetheresters include materials, whichare commercially available from DuPont under the tradename Hytrel®.Suitable thermoplastic polyetheramides include materials, which areavailable from Elf-Atochem under the tradename Pebax®. Other suitablematerials for the inner cover layer include nylon andacrylonitrile-butadiene-styrene copolymer (ABS).

[0074] In a second embodiment, a multi-layer cover formed by a sandwichinjection molding process, wherein said cover comprises three layers: aninner layer and an outer layer of a first material and an intermediatelayer therebetween of a second material. As illustrated in FIG. 3, asandwich cover 26 comprising outer cover layer 28, inner cover layer 30and intermediate cover layer 32. The sandwich injection molding processfor forming a multi-layer golf ball cover includes the steps of pushinga measured amount of a first plasticized material into one end of anaccumulation cylinder, pushing a measured amount of a second plasticizedmaterial into the opposite end of the accumulation cylinder, andinjecting both materials in a single plunging step, so that the firstmaterial substantially coats the surface of the mold while the secondmaterial substantially fills the interior of the first material. Thefirst plasticized material cools and solidifies when coming into contactwith the surface of the mold. When a lesser amount of the firstplasticized material and a faster injection rate are used, thinner innerand outer cover layers can be realized. Hence, a thinner mold cavity canbe used to produce a thin multi-layer cover in accordance to the presentinvention is realized. The sandwich injection molding process is fullydescribed in U.S. Pat. No. 5,783,293. The disclosure of the '293 patentis incorporated herein in its entirety. Sandwich injection molding golfball covers can also be accomplished with other commercially availableapparatus known to those of ordinary skill in the art.

[0075] In other preferred embodiment, additional suitable covermaterials include those disclosed in U.S. Pat. Nos. 6,419,535, 6,152,834and 5,919,100 and in international publication Nos. WO 00/23519 and WO00/57962. These references are incorporated by reference in theirentireties. Other suitable cover materials include any partially orfully neutralized ionomer, metallocene or other catalyzed polymers,silicone, other thermoplastic and thermoset elastomers and metal salt ofa fatty acid and a melt processible composition comprising a highlyneutralized ethylene copolymer and one or more aliphatic,mono-functional organic acids having fewer than 36 carbon atoms of saltsthereof, wherein greater than 90% of all the acid of the ethylenecopolymer is neutralized. The cover may also comprise a single layer.Alternatively, the cover materials may include a compression molded,injection molded, cast or reaction molded composition comprising athermoplastic or thermosetting polyurethane or polyurethane copolymer.

[0076] To craft a high moment of inertia ball, the cover layers 16, 18may have high density fillers, such as those described aboveincorporated therein so long as the cover layers are thin. In otherwords, one of the cover layers 16, 18, preferably the inner cover layer16, is a thin dense layer. Thin dense layer 16 may have a thickness fromabout 0.001 inch to about 0.05 inch (0.025 mm to 1.27 mm), morepreferably from about 0.005 inch to about 0.030 inch (0.127 mm to 0.76mm), and most preferably from about 0.010 inch to about 0.020 inch (0.25mm to 0.5 mm). Thin dense layer preferably has a specific gravity ofgreater than about 1.2, more preferably more than about 1.5, even morepreferably more than about 1.8 and most preferably more than about 2.0.Preferably, thin dense layer 16 is located as close as possible to theouter surface of the ball. The advantages of locating the thin denselayer as radially outward as possible have been discussed in detailabove. Preferably, the thin dense layer is located about 0.030 inch toabout 0.110 inch from the outer surface of the ball. It is, however,necessary to locate the thin dense layer outside of the centroid radius.

[0077] Except for the moment of inertia, the presence of the thin denselayer preferably does not appreciably affect the overall ballproperties, such as the feel, compression, coefficient of restitution,and cover hardness. Suitable materials for the thin dense layer includeany material that meets the specific gravity and thickness conditionsstated above. The thin dense layer is preferably applied to the core asa liquid solution, dispersion, lacquer, paste, gel, melt, etc., such asa loaded or filled natural or non-natural rubber latex, polyurethane,polyurea, epoxy, polyester, any reactive or non-reactive coating orcasting material, and then cured, dried or evaporated down to theequilibrium solids level. The thin dense layer may also be formed bycompression or injection molding, RIM, casting, spraying, dipping,powder coating, or any means of depositing materials onto the innercore. The thin dense layer may also be a thermoplastic polymer loadedwith a specific gravity increasing filler, fiber, flake or particulate,such that it can be applied as a thin coating and meets the preferredspecific gravity levels discussed above. One particular example of athin dense layer, which was made from a soft polybutadiene with tungstenpowder using the compression molded method, has a thickness of0.021-0.025 inch (0.53 mm-0.64 mm) and a specific gravity of 1.31 and aShore C hardness of about 72.

[0078] For reactive liquid systems, the suitable materials include anymaterial which reacts to form a solid such as epoxies, styrenatedpolyesters, polyurethanes or polyureas, liquid PBR's, silicones,silicate gels, agar gels, etc. Casting, RIM, dipping and spraying arethe preferred methods of applying a reactive thin dense layer.Non-reactive materials include any combination of a polymer either inmelt or flowable form, powder, dissolved or dispersed in a volatilesolvent. Suitable thermoplastics are disclosed in U.S. Pat. Nos.6,149,535 and 6,152,834.

[0079] Alternatively, one of the cover layers may be a loaded thin filmor “pre-preg” or a “densified loaded film,” as described in U.S. Pat.No. 6,010,411 (“the '411 patent) related to golf clubs, may be used asthe thin film layer in a compression molded or otherwise in a laminatedform applied inside the cover layer 36. The “pre-preg” disclosed in the'411 patent may be used with or without the fiber reinforcement, so longas the preferred specific gravity and preferred thickness levels aresatisfied. The loaded film comprises a staged resin film that has adensifier or weighing agent, preferably copper, iron or tungsten powderevenly distributed therein. The resin may be partially cured such thatthe loaded film forms a malleable sheet that may be cut to desired sizeand then applied to the outside of the core or inside of the cover. Suchfilms are available from the Cytec of Anaheim, Calif. or Bryte of SanJose, Calif.

[0080] Alternative to a high moment of inertia ball and a low moment ofinertia ball, a midrange moment of inertia ball with a relatively largeresilient deformation zone can be created. For example, the mid-rangeball may comprise a high density inner core 12, a large outer core 14,and thin dense layer 16 and a cover 18. Preferably, the inner core 12has high density fillers, such as zinc oxide or other filler withspecific gravity less than that of tungsten, incorporated in to apolymeric matrix, such as polyurethane or polybutadiene. The thin denselayer positioned radially outside of the centroid radius compensates forthe reduction in moment of inertia to produce a mid-range moment ofinertia ball.

[0081] While various descriptions of the present invention are describedabove, it is understood that the various features of the presentinvention can be used singly or in combination thereof. Therefore, thisinvention is not to be limited to the specifically preferred embodimentsdepicted therein.

What is claimed is:
 1. A golf ball comprising a core which comprises aninner core and an outer core, and which is encased by a cover having athickness from about 0.010 inch to about 0.040 inch, wherein the innercore has a specific gravity of at least about 5.0 and a diameter ofabout 0.750 inch or less and wherein the outer core comprisessubstantially no filler.
 2. The golf ball of claim 1, wherein thespecific gravity of the inner core is at least 6.5.
 3. The golf ball ofclaim 1, wherein the inner core comprises high specific gravity fillerincorporated in a polymeric matrix.
 4. The golf ball of claim 3, whereinthe high specific gravity filler comprises tungsten powder.
 5. The golfball of claim 3, wherein the high specific gravity filler is selectedfrom a group consisting of metal powder, metal alloy powder, metaloxide, metal searates, particulates and carbonaceous material.
 6. Thegolf ball of claim 3, wherein the high specific gravity filler isselected from a group consisting of bismuth powder, boron powder, brasspowder, bronze powder, cobalt powder, copper powder, inconel metalpowder, iron metal powder, molybdenum powder, nickel powder, stainlesssteel powder, titanium metal powder, zirconium oxide powder, aluminumflakes, tungsten metal powder, beryllium metal powder, zinc metalpowder, tin metal powder, zinc oxide, iron oxide, aluminum oxide,titanium dioxide, magnesium oxide, zirconium oxide and tungstentrioxide.
 7. The golf ball of claim 3, wherein the polymeric matrixcomprises polyurethane.
 8. The golf ball of claim 3, wherein thepolymeric matrix comprises polybutadiene.
 9. The golf ball of claim 3,wherein the polymeric matrix comprises a polymer selected from a groupconsisting of natural rubber, polybutadiene, polyisoprene,styrene-butadiene or styrene-propylene-diene rubber, ionomer resins,polyamides, polyesters, thermoplastic elastomer, polyether amidecopolymers, polyether ester copolymers, thermoplastic urethane, styrenicblock copolymers elastomers, metal salt of a fatty acid, partially orfully neutralized ionomer, metallocene or other catalyzed polymer,castable material, urethane, polyurea, epoxy, silicone, IPN, and a meltprocessible composition, which comprises a highly neutralized ethylenecopolymer and one or more aliphatic, mono-functional organic acidshaving fewer than 36 carbon atoms of salts thereof, wherein greater than90% of all the acid of the ethylene copolymer is neutralized.
 10. Thegolf ball of claim 1, wherein the diameter of the inner core is fromabout 0.25 inch to about 0.50 inch.
 11. The golf ball of claim 10,wherein the diameter of the inner core is from about 0.40 inch to about0.5 inch.
 12. The golf ball of claim 1, wherein the inner core comprisesa metal sphere.
 13. The golf ball of claim 12, wherein the inner corecomprises a steel sphere.
 14. The golf ball of claim 1, wherein theouter core comprises a polybutadiene having a Mooney viscosity fromabout 40 to about
 80. 15. The golf ball of claim 14, wherein the Mooneyviscosity is from about 40 to about
 60. 16. The golf ball of claim 14,wherein the compression of the outer core is less than about
 70. 17. Thegolf ball of claim 1, wherein the outer core comprises a polymerselected from a group consisting of natural rubber, polybutadiene,polyisoprene, styrene-butadiene or styrenepropylene-diene rubber,ionomer resins, polyamides, polyesters, thermoplastic elastomer,polyether amide copolymers, polyether ester copolymers, thermoplasticurethane, styrenic block copolymers elastomers, metal salt of a fattyacid, partially or fully neutralized ionomer, metallocene or othercatalyzed polymer, castable material, urethane, polyurea, epoxy,silicone, IPN, and a melt processible composition, which comprises ahighly neutralized ethylene copolymer and one or more aliphatic,mono-functional organic acids having fewer than 36 carbon atoms of saltsthereof, wherein greater than 90% of all the acid of the ethylenecopolymer is neutralized.
 18. The golf ball of claim 1, wherein theouter core has a specific gravity in the range of about 1.0 to about1.1.
 19. The golf ball of claim 1, wherein the filler content in theouter core is less than about 3 phr to 100 phr of polymeric corematerial.
 20. The golf ball of claim 17, wherein the outer core furthercomprises sulphur compound.
 21. The golf ball of claim 1, wherein thecover thickness is about 0.010 inch to 0.030 inch.
 22. The golf ball ofclaim 1, wherein the cover is a sandwich cover and wherein the sandwichcover comprises an inner cover layer and outer cover layer comprising afirst polymeric material and an intermediate cover layer comprising asecond polymeric material.
 23. The golf ball of claim 1, wherein thecover comprises an inner cover layer and an outer cover layer.
 24. Thegolf ball of claim 1, wherein the cover comprises an ionomer having aShore D hardness of greater than about
 60. 25. The golf ball of claim24, wherein the Shore D hardness is greater than
 65. 26. The golf ballof claim 25, wherein the Shore D hardness is greater than 70
 27. Thegolf ball of claim 1, wherein the cover comprises a urethane having aShore D hardness of less than about
 65. 28. The golf ball of claim 27,wherein the urethane has a Shore D hardness of about 30 to about
 60. 29.The golf ball of claim 1, wherein the cover comprises a materialselected from a group consisting of polyurethane, partially or fullyneutralized ionomer, polyurea, polyurethane ionomer, metallocene orother catalyzed polymer, silicone, metal salt of a fatty acid and meltprocessible composition, which comprises a highly neutralized ethylenecopolymer and one or more aliphatic, mono-functional organic acidshaving fewer than 36 carbon atoms of salts thereof, wherein greater than90% of all the acid of the ethylene copolymer is neutralized.
 30. A golfball comprising a thin dense layer encasing a core, wherein the thindense layer is encased by a cover, wherein the thin dense layer has aspecific gravity of greater than about 1.2 and a thickness from about0.001 to about 0.050 inch; and wherein the core is a non-wound corehaving a specific gravity of less than the specific gravity of the thindense layer, a diameter from about 1.54 to about 1.64 inches and whereinthe core has substantially no filler.
 31. The golf ball of claim 30,wherein the specific gravity of the thin dense layer is greater than1.5.
 32. The golf ball of claim 31, wherein the specific gravity of thethin dense layer is greater than 1.8.
 33. The golf ball of claim 32,wherein the specific gravity of the thin dense layer is greater than2.0.
 34. The golf ball of claim 30, wherein the thickness of the thindense layer is from about 0.005 inch to 0.030 inch.
 35. The golf ball ofclaim 34, wherein the thickness of the thin dense layer is from about0.010 inch to 0.020 inch.
 36. The golf ball of claim 30, wherein thethin dense layer comprises a densified loaded film.
 37. The golf ball ofclaim 30, wherein the filler content in the core is less than about 3phr to 100 phr of polymeric core material.
 38. The golf ball of claim 30further comprises a second core layer.
 39. The golf ball of claim 38,wherein the second core layer surrounds the core layer.
 40. The golfball of claim 38, wherein the core layer surrounds the second corelayer.
 41. The golf ball of claim 38, wherein the second core layer is aliquid filled innermost core.
 42. The golf ball of claim 38, wherein thesecond core layer is a hollow innermost core.
 43. The golf ball of claim38, wherein the second core layer is an innermost core having a specificgravity of greater than about 5.0.
 44. The golf ball of claim 43,wherein the second core layer has a diameter of less than about 0.75inch.
 45. The golf ball of claim 44, wherein the second core layer has adiameter from about 0.25 inch to about 0.5 inch.
 46. The golf ball ofclaim 45, wherein the second core layer has a diameter from about 0.40inch to about 0.50 inch.
 47. The golf ball of claim 30, wherein thecover comprises an inner cover layer and an outer cover layer.
 48. Thegolf ball of claim 30, wherein the cover is a sandwich cover and whereinthe sandwich cover comprises an inner cover layer and outer cover layercomprising a first polymeric material and an intermediate cover layercomprising a second polymeric material.
 49. The golf ball of claim 30,wherein the cover comprises a material selected from a group consistingof polyurethane, partially or fully neutralized ionomer, polyurea,polyurethane ionomer, metallocene or other catalyzed polymer, silicone,metal salt of a fatty acid and melt processible composition, whichcomprises a highly neutralized ethylene copolymer and one or morealiphatic, mono-functional organic acids having fewer than 36 carbonatoms of salts thereof, wherein greater than 90% of all the acid of theethylene copolymer is neutralized.
 50. The golf ball of claim 30,wherein the cover has a thickness of about 0.010 inch to about 0.040inch.
 51. The golf ball of claim 50, wherein the cover has a thicknessof about 0.010 inch to about 0.030 inch.
 52. The golf ball of claim 30,wherein the core comprises a polymer selected from a group consisting ofnatural rubber, polybutadiene, polyisoprene, styrene-butadiene orstyrenepropylene-diene rubber, ionomer resins, polyamides, polyesters,thermoplastic elastomer, polyether amide copolymers, polyether estercopolymers, thermoplastic urethane, styrenic block copolymerselastomers, metal salt of a fatty acid, partially or fully neutralizedionomer, metallocene or other catalyzed polymer, castable material,urethane, polyurea, epoxy, silicone, IPN, and a melt processiblecomposition, which comprises a highly neutralized ethylene copolymer andone or more aliphatic, mono-functional organic acids having fewer than36 carbon atoms of salts thereof, wherein greater than 90% of all theacid of the ethylene copolymer is neutralized.
 53. A golf ballcomprising a thin dense layer encasing a core, wherein the thin denselayer is encased by a cover, wherein the thin dense layer has a specificgravity of greater than 1.2 and a thickness from about 0.001 to about0.050 inch, and the thin dense layer is positioned at a radial distanceoutside of the centroid radius; wherein the core is a non-wound corehaving a specific gravity of less than the specific gravity of the thindense layer, a diameter from about 1.54 to about 1.64 inches and acompression of less than 90; wherein the core comprises an inner corehaving a diameter from about 0.50 inch to about 1.54 inches and aspecific gravity of less than 0.9.
 54. The golf ball of claim 53,wherein the inner core comprises substantially no filler.
 55. The golfball of claim 53, wherein the cover has a Shore D hardness of less than65.
 56. The golf ball of claim 54, wherein the cover has a Shore Dhardness of less than
 60. 57. The golf ball of claim 53, wherein thecore further comprises an outer core, wherein the outer core hasthickness of about 0.05 inch to about 0.575 inch and a specific gravityof about 0.5 to 1.05.
 58. The golf ball of claim 57, wherein the outercore comprises substantially no filler.
 59. The golf ball of claim 57,wherein the outer core has a specific gravity of about 0.8 to about0.96.
 60. The golf ball of claim 57, wherein the specific gravity of theouter core is higher than the specific gravity of the inner core. 61.The golf ball of claim 53, wherein the core comprises a polymer selectedfrom a group consisting of partially or fully neutralized ionomer,metallocene or other catalyzed polymer, polyurethane, silicone,thermoplastic elastomer, thermosetting elastomer, metal salt of a fattyacid, and melt processible composition, which comprises a highlyneutralized ethylene copolymer and one or more aliphatic,mono-functional organic acids having fewer than 36 carbon atoms of saltsthereof, wherein greater than 90% of all the acid of the ethylenecopolymer is neutralized.
 62. The golf ball of claim 53, wherein thecover comprises a material selected from a group consisting ofpolyurethane, partially or fully neutralized ionomer, polyurea,polyurethane ionomer, metallocene or other catalyzed polymer, silicone,metal salt of a fatty acid and melt processible composition, whichcomprises a highly neutralized ethylene copolymer and one or morealiphatic, mono-functional organic acids having fewer than 36 carbonatoms of salts thereof, wherein greater than 90% of all the acid of theethylene copolymer is neutralized.
 63. The golf ball of claim 53,wherein the cover comprises a polymer selected from a group consistingof compression molded thermoset polyurethane, compression moldedthermoplastic polyurethane, compression molded thermoset polyurethanecopolymer, compression molded thermoplastic polyurethane copolymer,injection molded thermoset polyurethane, injection molded thermoplasticpolyurethane, injection molded thermoset polyurethane copolymer,injection molded thermoplastic polyurethane copolymer, reactioninjection molded thermoset polyurethane, reaction injection moldedthermoplastic polyurethane, reaction injection molded thermosetpolyurethane copolymer, reaction injection molded thermoplasticpolyurethane copolymer, cast thermoplastic polyurethane, castthermosetting polyurethane, cast thermoplastic polyurethane copolymer,and cast thermosetting polyurethane copolymer.
 64. The golf ball ofclaim 53, wherein in the core comprises a polymer selected from a groupconsisting of chemically foamed thermoplastic, physically foamedthermoplastic, chemically foamed thermoset and physically foamedthermoset.
 65. A golf ball comprising: a core, an outer core, ahigh-specific-gravity layer disposed around the core wherein said layerhaving a thickness between about 0.001 and about 0.050 inches and aspecific gravity of greater than 1.8, and a cover of at least one layerdisposed around the high-specific-gravity layer, wherein said corecomprises a specific-gravity-reducing agent, and a diameter from about0.50 inch to about 1.54 inches and a specific gravity of less than 0.9,and wherein the outer core has thickness of about 0.05 inch to about0.575 inch and a specific gravity of about 0.5 to about 1.05.
 66. Thegolf ball of claim 65, wherein the cover has a Shore D hardness of lessthan
 65. 67. The golf ball of claim 66, wherein the cover has a Shore Dhardness of less than
 60. 68. The golf ball of claim 65, wherein theouter core has a specific gravity of about 0.8 to about 0.96.
 69. Thegolf ball of claim 68, wherein the outer core comprises substantially nofiller.
 70. The golf ball of claim 65, wherein the specific gravity ofthe outer core is higher than the specific gravity of the inner core.71. The golf ball of claim 65, wherein the core comprises a polymerselected from a group consisting of partially or fully neutralizedionomer, metallocene or other catalyzed polymer, polyurethane, silicone,thermoplastic elastomer, thermosetting elastomer, metal salt of a fattyacid, and melt processible composition, which comprises a highlyneutralized ethylene copolymer and one or more aliphatic,mono-functional organic acids having fewer than 36 carbon atoms of saltsthereof, wherein greater than 90% of all the acid of the ethylenecopolymer is neutralized.
 72. The golf ball of claim 65, wherein thecover comprises a material selected from a group consisting ofpolyurethane, partially or fully neutralized ionomer, polyurea,polyurethane ionomer, metallocene or other catalyzed polymer, silicone,metal salt of a fatty acid and melt processible composition, whichcomprises a highly neutralized ethylene copolymer and one or morealiphatic, mono-functional organic acids having fewer than 36 carbonatoms of salts thereof, wherein greater than 90% of all the acid of theethylene copolymer is neutralized.
 73. The golf ball of claim 65,wherein the cover comprises a polymer selected from a group consistingof compression molded thermoset polyurethane, compression moldedthermoplastic polyurethane, compression molded thermoset polyurethanecopolymer, compression molded thermoplastic polyurethane copolymer,injection molded thermoset polyurethane, injection molded thermoplasticpolyurethane, injection molded thermoset polyurethane copolymer,injection molded thermoplastic polyurethane copolymer, reactioninjection molded thermoset polyurethane, reaction injection moldedthermoplastic polyurethane, reaction injection molded thermosetpolyurethane copolymer, reaction injection molded thermoplasticpolyurethane copolymer, cast thermoplastic polyurethane, castthermosetting polyurethane, cast thermoplastic polyurethane copolymer,and cast thermosetting polyurethane copolymer.
 74. The golf ball ofclaim 65, wherein in the core comprises a polymer selected from a groupconsisting of chemically foamed thermoplastic, physically foamedthermoplastic, chemically foamed thermoset and physically foamedthermoset.